Buster/lightdm - after locking screen, unlock prompt not visible

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Buster/lightdm - after locking screen, unlock prompt not visible

Raj Kiran Grandhi-3
Hi,

In a fresh install of Buster with XFCE desktop, locking the screen
blanks the monitor and the monitor enters a power save state. After
that, neither moving the mouse nor typing on the keyboard would turn
the monitor back on.

Typing the password without any visual feedback (while the monitor
continues to be in the power save state) unlocks the screen and my
session is displayed normally.

Also, switching to another VT when the monitor turns off and switching
back displays the unlock prompt normally.

The closest I could find online was this:
https://bbs.archlinux.org/viewtopic.php?id=240200 wherein installing
the nouveau video driver appeared to have fixed the issue. However,
that solution is not applicable in my case as I have an integrated
intel graphics controller.

Is anybody else experiencing this bug? Any workaround?

Thanks,
Raj Kiran

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Re: Buster/lightdm - after locking screen, unlock prompt not visible

Jape Person
On 5/31/19 11:16 AM, Raj Kiran Grandhi wrote:

> Hi,
>
> In a fresh install of Buster with XFCE desktop, locking the screen
> blanks the monitor and the monitor enters a power save state. After
> that, neither moving the mouse nor typing on the keyboard would turn
> the monitor back on.
>
> Typing the password without any visual feedback (while the monitor
> continues to be in the power save state) unlocks the screen and my
> session is displayed normally.
>
> Also, switching to another VT when the monitor turns off and switching
> back displays the unlock prompt normally.
>
> The closest I could find online was this:
> https://bbs.archlinux.org/viewtopic.php?id=240200 wherein installing
> the nouveau video driver appeared to have fixed the issue. However,
> that solution is not applicable in my case as I have an integrated
> intel graphics controller.
>
> Is anybody else experiencing this bug? Any workaround?
>
> Thanks,
> Raj Kiran
>
>
Hi, Raj.

Behavior on my testing systems with Xfce desktop environment is exactly
as you describe. I didn't think of it as a bug. There are lots of
lightweight lockers which behave similarly -- presenting a blank screen,
or perhaps a colored screen and awaiting password input without any kind
of feedback until the correct password is entered and the desktop
returns to normal.

I'm grateful for your post. I had never bothered to switch terminals to
see if it would have an effect. When I do so on these systems, I'm
presented with a screen with a message which says that the system is
locked and that I will be redirected to a login prompt in a few seconds.

I hope this is useful. Thank you for your post, as I prefer using a
prompt to typing my password at a blank screen.

Regards,
jp

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Re: Buster/lightdm - after locking screen, unlock prompt not visible

Cindy Sue Causey
In reply to this post by Raj Kiran Grandhi-3
On 5/31/19, Raj Kiran Grandhi <[hidden email]> wrote:

> Hi,
>
> In a fresh install of Buster with XFCE desktop, locking the screen
> blanks the monitor and the monitor enters a power save state. After
> that, neither moving the mouse nor typing on the keyboard would turn
> the monitor back on.
>
> Typing the password without any visual feedback (while the monitor
> continues to be in the power save state) unlocks the screen and my
> session is displayed normally.
>
> Also, switching to another VT when the monitor turns off and switching
> back displays the unlock prompt normally.
>
> The closest I could find online was this:
> https://bbs.archlinux.org/viewtopic.php?id=240200 wherein installing
> the nouveau video driver appeared to have fixed the issue. However,
> that solution is not applicable in my case as I have an integrated
> intel graphics controller.
>
> Is anybody else experiencing this bug? Any workaround?


Hi, sorry, no direct answer, BUT... #1 this just came up fairly
recently. If it was you, never mind, grin.

If not, it was the same deal where they had the presence of mind to
try that trick of typing in the password anyway... and #ItWORKS (as a
temporary work-around). Maybe that thread's easily findable in the
archive if it was not you previously? I don't remember the outcome for
that one.

#2 A WEIRD coincidence of a stumbled upon late last night. I was
wanting to commiserate with a different thread related to Wifi and
failed modules "polling". That landed me at /var/log/syslog and
friends. While scouring that, I noticed this ODD message in there:

linux intel_powerclamp: No package C-state available

*hm!* Um.. *hm?* :D

Researching it landed the following among a lot of other things
(*waving at kernel[newbies]):

https://www.kernel.org/doc/Documentation/thermal/intel_powerclamp.txt

I THINK that just kind of talks about it. WHY I'm not hesitating to
post it at this point is because I'm seeing references like "sleep
state" in the various blurbs that pulled up for my own search last
night. "Sleep" and "wakeups" do get a head nod in that Kernel doc
there.

Oh, and that word "intel" in mine and then you mentioned it, too, is
why I went ahead and shared this here. May not be directly related,
but it *does* seem to be in the nearby sleep and hibernate and
*successfully (emphasis on "fully")* resume, yada-yada ballpark. If
not appropriate for this, it's a thought seed planted as a checkpoint
for past and future threads of this type. :)

If nothing else, it's like what happened with mine last night. Go
poking around at one thing... like just how DOES C-state get addressed
under the hood... and maybe in the meantime, someone accidentally
trips on the trigger line of code that's causing an occasional
sleep/hibernate session to not bring that password prompt GUI back
into view..

Could that be a line of code residing in each, our personal CHOICE of
login manager?

As I'm still thinking on this before sending: Lockscreen doesn't
necessarily imply hibernate/sleep state. Maybe that's a place for a
glitch to occur.

Maybe... there's a missing line of code that would tell it that hey,
you weren't asleep but let's pretend you were so we need to do what we
do if you HAD been asleep > push this button/release that one so that
yada-yada is freed up enough to trigger that password prompt GUI to
squeeze its way through and back onto the screen...

PS For newbies'ish wondering what you might learn next about your own
setups, if you haven't found it already, check out that..
/var/log/syslog in its various forms (.1, .gz, etc). Never know what
you might find in there that could lead to more learning about how
your own system works. I forget to peek in there when I'm bored, but
it's been a helpful self-education trigger for me over time.

Cindy :)
--
Cindy-Sue Causey
Talking Rock, Pickens County, Georgia, USA

* runs with birdseed *

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Re: Buster/lightdm - after locking screen, unlock prompt not visible

Brian
In reply to this post by Jape Person
On Fri 31 May 2019 at 12:19:31 -0400, Jape Person wrote:

> On 5/31/19 11:16 AM, Raj Kiran Grandhi wrote:
> > Hi,
> >
> > In a fresh install of Buster with XFCE desktop, locking the screen
> > blanks the monitor and the monitor enters a power save state. After
> > that, neither moving the mouse nor typing on the keyboard would turn
> > the monitor back on.
> >
> > Typing the password without any visual feedback (while the monitor
> > continues to be in the power save state) unlocks the screen and my
> > session is displayed normally.
> >
> > Also, switching to another VT when the monitor turns off and switching
> > back displays the unlock prompt normally.
> >
> > The closest I could find online was this:
> > https://bbs.archlinux.org/viewtopic.php?id=240200 wherein installing
> > the nouveau video driver appeared to have fixed the issue. However,
> > that solution is not applicable in my case as I have an integrated
> > intel graphics controller.
> >
> > Is anybody else experiencing this bug? Any workaround?
> >
> > Thanks,
> > Raj Kiran
> >
> >
> Hi, Raj.
>
> Behavior on my testing systems with Xfce desktop environment is exactly
> as you describe. I didn't think of it as a bug. There are lots of

The opinion is that it is a bug. See

https://lists.debian.org/debian-devel/2019/06/msg00000.html

--
Brian.

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Re: Buster/lightdm - after locking screen, unlock prompt not visible

Raj Kiran Grandhi-3
> The opinion is that it is a bug. See
>
> https://lists.debian.org/debian-devel/2019/06/msg00000.html

Thank you for the feedback. I have filed a bug report for this issue.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=929834

Please note that this issue does not occur if using the slick-greeter instead.

Raj Kiran.